There's no dramatic differences between pro & basic. The look identical. They perform very similarly. Internally Pro has some small engine improvements. Many people consider pro more-so as a donation to the developers to help them continue developing it. So what are the improvements you ask ... tends to get turbo charged connection more consistently than basic. Is better for finding the rarer files. Connects to 5 ultrapeers instead of 3. Can download from 10 hosts per download instead of 8. Although that also depends on your connection speed & setting. T3 users can downld from more. But overall, the improvement is better for those rarer files. For common files you won't see too much difference. Dial up users won't see any difference.